mirror of
https://github.com/vgmstream/vgmstream.git
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59 lines
1.7 KiB
C
59 lines
1.7 KiB
C
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#include "ngc_afc_decoder.h"
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#include "../util.h"
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const short afc_coef[16][2] =
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{{0,0},
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{0x0800,0},
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{0,0x0800},
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{0x0400,0x0400},
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{0x1000,0xf800},
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{0x0e00,0xfa00},
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{0x0c00,0xfc00},
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{0x1200,0xf600},
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{0x1068,0xf738},
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{0x12c0,0xf704},
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{0x1400,0xf400},
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{0x0800,0xf800},
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{0x0400,0xfc00},
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{0xfc00,0x0400},
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{0xfc00,0},
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{0xf800,0}};
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void decode_ngc_afc(VGMSTREAMCHANNEL * stream, sample * outbuf, int channelspacing, int32_t first_sample, int32_t samples_to_do) {
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int i=first_sample;
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int32_t sample_count;
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int framesin = first_sample/16;
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int8_t header = read_8bit(framesin*9+stream->offset,stream->streamfile);
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int32_t scale = 1 << ((header>>4) & 0xf);
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int coef_index = (header & 0xf);
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int32_t hist1 = stream->adpcm_history1_16;
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int32_t hist2 = stream->adpcm_history2_16;
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int coef1 = afc_coef[coef_index][0];
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int coef2 = afc_coef[coef_index][1];
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/*printf("offset: %x\nscale: %d\nindex: %d (%lf,%lf)\nhist: %d %d\n",
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(unsigned)stream->offset,scale,coef_index,coef1/2048.0,coef2/2048.0,hist1,hist2);*/
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first_sample = first_sample%16;
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for (i=first_sample,sample_count=0; i<first_sample+samples_to_do; i++,sample_count+=channelspacing) {
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int sample_byte = read_8bit(framesin*9+stream->offset+1+i/2,stream->streamfile);
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outbuf[sample_count] = clamp16((
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(((i&1?
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get_low_nibble_signed(sample_byte):
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get_high_nibble_signed(sample_byte)
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) * scale)<<11) +
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(coef1 * hist1 + coef2 * hist2))>>11
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);
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/*printf("%hd\n",outbuf[sample_count]);*/
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hist2 = hist1;
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hist1 = outbuf[sample_count];
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}
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stream->adpcm_history1_16 = hist1;
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stream->adpcm_history2_16 = hist2;
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}
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